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Tonight we will create our own light pillar at the middle of the lake (we got the stuff in the local shop in Kilpisjärvi). The lake is flat and we will most likely not be disturbed by cars or village lights.

A 20 minutes snowmobile drive later we are on the lake, install our LED floodlight and pose for the camera. Then we switch it on and off and take images from different spots.

Again we have to kneel down - this time all four (Franz, Joonatan, Konstantin and I)....Joonatan
is making jokes at some stage as we all kneel down in a circle "We
praise the ancient gods of mount Saana". It must look really like a strange ritual.....

Finally, Joonatan tells the legend oft Lake Kilpisjärvi and the landscape in the region - a legend about the giants Malla and Saana. In the end Saana (the bride) formed the lake from her tears. Read the story here.

It is very awesome listening to the tale while kneeling down in front of our Canon camera....and while Joonatans story continues a dim a…

The Kilpisjärvi biological station in winter is a nice place for a stay. It is not busy at all, but still you meet some other researchers to discuss new ideas. It is well equipped (with stuff like sleighs, snow shoes and ski) and has an own cantine that serves breakfast and dinner. We had nice food here including the very local reindeer meat dish.

The station is famous for the research on lemmings. They are part of the logo, you can read an article in the hallway and look at (touch?) some lemming fur.

On the last day in Kilpisjärvi we don't have to drill holes anymore. We can inspect data, take down our installed measurement devices and start to pack. We watch our lake physicist friends unpack their ROV (remotely operated underwater vehicle) a nice device that is built to skate (!) just under the ice taking measurements.....

We forgot to take daytime pictures with our all-sky fisheye lens camera - so we take a walk down to the lake.

If one wants to evaluate the impact of light pollution on lakes (or other ecosystems) it is required to put it in context with natural nocturnal but also with daylight. Daylight is supposed to be a lot. If you look into a text book it is 100 000 lx or a bit more....well here in the sub-arctics (Kilpisjärvi is at about 69° N) just 1 month after winter solstice it peaks at around 600 lx on a cloudy "day" (that is less then the textbook value at sunset of around 800lx).

Todays task is to measure the light on the lake and under the ice. So Franz and I jump back into our cool explorer suits and pull the seldge with the equipment onto the lake, where the snowmobile is waiting for a fun ride.

Our lake physics friends drop us off about 500 m from shore with our generator, light measurement devices, shovel, sledge and a drill. Although they have no time, they show us how to drill the hole in the ice....

Their task today is to do a transect. That means measuring temperature gradient …

It was fun being in the snowy desert during day - but our misssion is to measure light at night. After dinner Franz and I hit the road...we earn confused looks from our lake physics friends..."You want to get out now? Not go to sauna after this busy and cold day?" - Aaargh thanks for the reminder ;)

When outside, we are amazed by the view above Kilpisjärvi village. The ice fog creates "light pillars" a phenomenon where flat ice crystals float in the lower atmosphere and create some sort of giant mirror reflecting only the light emitted directly upwards towards your observation point (see wikipedia here and nicer pictures on twitter). These pillars look bizarrely and the most spectacular thing is that every car approaching us is creating the same moving "light pillar"....pretty stunning.

During our hunt for darkness we measure night sky brightness values down to 21.5-21.6 mags (so near natural). Every now and then ice-fog or clouds appear and either light …

In the morning we meet our IGB colleague Georgiy and his team consting of two Russians from Irkutsk: Konstantin and Ilja and Joonathan from Finland. They are all lake physicists interested in the dynamics of the water under the ice.

Today's task is to install some devices on the ice of Lake Kilpisjärvi. The lake is frozen with ice thickness about 50 cm at the moment. I am allowed to join the other physicists to go on the lake. First task is to fit the warm and safe winter working suit, then we take the snowmobile and I take a seat in the sledge where we can store equipment. It is a bumpy ride with two Siberians and a Kasach......

First job is finding the place for the installations. Yesterday a hole was drilled through the ice and we are supposed to drop some underwater measurement devices there. However it was snowing and storming all night and its not an easy task. It is somehow spooky when you here someone with a Russian accent yelling "We cant find hole" while you s…